Hammer mill structure



H. C. JACOBSON HAMMER MILL STRUCTURE Oct. 18, 1966 5 Sheets-Sheet 1 Filed 001;. '7, 1963 i 5 l N I, I

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Oct. 18, 1966 H. c. JACOBSON 3,279,707

' HAMMER MILL STRUCTURE Filed Oct. '7, 1965 5 Sheets-Sheet 2 FIG. 3

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INVENTOR. Hon/42p 6'. 079001350 Oct. 18, 1966 H. c. JACOBSON HAMMER MILL STRUCTURE 5 Sheets-Sheet 5 Filed Oct. '7, 1963 m: v4 m] C o w W H United States Patent 3,279,707 HAMMER MILL STRUCTURE Howard C. Jacobson, Minneapolis, Minn, assignor to Northwestern National Bank of Minneapolis, Minneapolis, Minn.

Filed Oct. 7, 1963, Ser. No. 314,147 6 Claims. (Cl. 24149) This invention relates to a new and useful improvement in a grinding mill structure, and more particularly in the type of a grinding mill structure referred to as a hammer mill.

-It is an object of this invention to provide for a full circle grinding operation.

It is another object of this invention to provide an improvement in a hammer mill screen design and construction such that material to be ground does not recirculate and build up on the screen, but is constantly returned into the hammers.

It is also an object of this invention to provide such efficient and eifective air circulation Within the grinding chamber that there is no need for an external dust collector.

It is a further object of this invention to provide an improved structure in a screen cover to substantially improve the air circulation within the grinding chamber.

It is also an object of this invention to provide an improved construction of a feed inlet into the grinding chamber for a continuous flow of material, which material flow is aided by the operation of the hammers within the grinding chamber.

These and other objects and advantages of the invention will be fully set forth in the following description made in connection with the accompanying drawings in which like reference characters refer to similar parts throughout the several views and in which:

FIG. 1 is a view of applicants device in front elevation;

FIG. 2 is a view of applieants device in side elevation with a portion thereof broken away;

FIG. 3 is a view in longitudinal vertical section on an enlarged scale taken on line 33 of FIG. '1 as indicated, and with some portions thereof being broken away and some portions shown in dotted line in alternate position;

FIG. 4 is a View similar to FIG. 1 on a reduced scale with a cover portion thereof being removed;

FIG. 5 is a view in vertical section taken on line 55 of FIG. 3 as indicated by the arrows, and with some portions thereof being shown in dotted line;

FIG. 6 is an exploded view in vertical section of a broken away portion of applicants device; and

FIG. 7 is a view in perspective of a detail of applicants device.

Referring to the drawings, a preferred embodiment of applicants apparatus is shown indicated generally by the character 10 and comprising a housing portion 12 substantially parallelepiped in form having side walls 13 and 14 and a top wall 15. Some wall portions are flanged at their bottoms in a conventional manner. The rear side of said portion 12 is open having an angled frame member 16 extending across the upper portion thereof.

Projecting forwardly of said housing portion 12 is a housing portion 20 of substantially reduced height having 3,279,707 Patented Oct. 18, 1966 ice side walls 22 and 23 forming extensions of said side walls 13 and 14 and having an arcuate top wall 25.

The wall 18 forms a common wall between said housing portions 12 and 20 forming the front wall of the former housing portion and the rear wall of said latter housing portion.

Said housing portion 20 has a front wall 26 of small width which in turn has a forwardly projecting flange portion 28 defining the opening 30 into the chamber 31 formed within said housing portion 20. An inclined strip or plate member 24 having inwardly inclined side wall portions at either end thereof extends across between the bottom ends of said flange portions leading into a discharge outlet 27 formed as the bottom of said chamber 31. Said chamber 31 has inclined lower side wall portions 22a and 23a which together with said plate member 24 define the opening of said discharge outlet 27.

Extending rearwardly of said housing portion 12 is a ground supported relatively low base portion 32 support ing a motor 33 of conventional design and having a drive shaft 34 connected by a coupling means 35 to a driven shaft 36 extending within said chamber 31. Said shaft 36 is appropriately jour-naled in bearing blocks 39 carried on a supporting shelf 40 mounted between the wall 16 and a supporting wall 19 in connection with said housing portion 12. Said shaft has journaled on the forwardly extending portion thereof a rotor assembly 42 having secured about the periphery thereof in a conventional manner a plurality of swing hammers 44. Said rotor assembly equipped with said hammers is of conventional design and is indicated generally by the character 45 as a hammer assembly.

A flange 48 extends forwardly of said wall 18 into said chamber 31 defining a tear drop configuration having its apex portion at the top thereof. Extending forwardly of said wall 18 from within the apex portion of said flange 48 is an arm type of bracket 50 indicated here as being angular in cross section.

Adapted to be carried on said bracket and mounted on said flange is a screen 53. With particular reference to FIG. 7, screen 53 is shown in a preferred embodiment formed of a fiat sheet screen material of suitable mesh which is substantially rectangular in blank and having a width to extend the full width of said hammer assembly. Said screen is curved to have a tear drop configuration in plan corresponding with the configuration of said flange 48 and the free ends of said screen are angled outwardly and form the apex thereof. An angled bracket 56 comprises a portion overlying said free ends of said screen and a mating portion underlying said free ends which together with bolts 58 holds the same in locked engagement. Said bracket 56 with said screen depending therefrom in operating position is carried on said bracket 50 with the inner edge portions of said screen over-lying said flange 48 and bearing the adjacent surface of said wall 18. The hammer assembly will be contained within said screen and thus formed within said screen is a grinding chamber 60.

Overlying the open end of said screen 53 is a cover member 63 of flat sheet material having a somewhat inset inwardly extending flange 64 to be received within the adjacent edge portion of said screen. Said cover member is provided with a pair of transversely spaced handles 65. Substantially centrally of said cover member 63 and axially aligned with said hammer assembly is an aperture shown as a circular opening 66 which forms an air inlet. It is noted with reference to FIG. 5 that there is ample space about said screen 53 within the chamber 31 for circulation of air whereby said chamber 31 forms an air circulation chamber.

Overlying said screen cover member 63 to hold the same in operating position is an outer cover member 68 having a configuration in plan of the flange portion 28 and having a forwardly extending rim portion 69 adapted to be received within said flange Z8 and to bear against a stop rib 28b formed within said ilange. Said cover member 68 has spaced projecting lugs 70 integral with the rim portion 69 which are shown reinforced by connecting ribs 70a. Carried on said cover are handles 71. Spaced about the outer side of said flange in alignment with said lugs are toggle clamps 72 of conventional design adapted to embrace said lugs and bear against the same with hand screws 73 carried thereby.

Carried by said cover member 68 are spaced holddown thumb screws 74 threaded through bosses 75 integral with the inner side of said cover. Said screws are adapted to bear against said screen cover 63 to hold the same secure in operating position.

Referring now to FIGS. 3 and 5, the housing portion 12 has disposed therein a hopper having in common with said housing portion its front wall 18. Said hopper has side walls 81 and 82 and a rear wall 83. Said rear wall has an inwardly or forwardly inclined lower portion 83a. The side walls 81 and 82 respectively are reduced in width to correspond to the configuration of said rear wall. Said hopper terminates in connection with a slot 112 as will be described.

The inclined portion 83a of said rear Wall 83 has an opening 84 therein overlaid by a magnet loaded plate member 86 secured by a hinge 87 at its lower portion and secured by a clamping bar or handle 88 at its upper end portion. This is a conventional cleanout door and the magnet therein collects metallic articles from the material fed into the hopper, Said bar or handle 88 will be appropriately pivoted to said plate member 86.

Inclined downwardly from front to back of said hopper to feed material onto said inclined wall portion 83a is a baffle plate member M).

Secured to either inner side of said side walls 81 and 82 at either side of said front wall 18 substantially centrally vertically thereof within said hopper 80 are a pair of ways 93 within which is vertically disposed a plate door member 94 having in connection therewith linkage 95 comprising a stub or lug portion 96 extending outwardly thereof having a connecting link 97 pivoted thereto and having an elongated crank 98 pivoted to the other end thereof with the free end 98a of said crank being secured to a bar 100 extending therethrough and rigid therewith. Said bar will have its inner end journaled in a boss 102 carried on the wall 81. Said bar will extend through the wall 82 to be journaled through a boss 103 carried on the wall 14 and has secured to the outwardly extending free end thereof a hand lever 105 by which said bar will be rotated to operate said linkage in raising and lowering the door 94.

Said handle 105 has pivoted thereto the inner end of a hand screw 107 threaded through a boss 108 riding on the outer side of an arcuate bracket 10$ having therein an arcuate slot 110 through which slot is disposed the shank of said hand screw. Hence said handle 105 in being swung upwardly or downwardly will be secured in any given position within the extent of the arcuate slot 110 by tightening the hand screw 107.

Formed in said wall 18 is the slot 112 having substantially parallel upper and lower walls providing an inlet into the grinding chamber 60, as illustrated in FIG. 5. Said slot is arcuately curved having for its greater extent a radius which substantially coincides with the radius of the path described by the hammers 44. It will be noted that the upper portion of said slot tends away from the curvature of the lower portion thereof having a radius of greater extent and thereby straightening out somewhat the curvature of said slot to provide an increase in the pitch or slope thereof.

With respect to said slot 112, said side wall 82 has its lower portion 82b angled inwardly to extend transversely of said wall 18 conforming longitudinally to the curvature of the lower side or wall of said slot 112 being integral therewith and flush therewith. Said lower portion 82b inclines downwardly somewhat transversely in the direction of said slot and tapers in width as it extends along said slot to merge into the wall 18 in the plane thereof at the point 112a of said slot. The rear wall portion 83a at its lower end will conform to the taper and longitudinal curvature of said wall portion 82b and merges into wall 18 in the plane thereof at the point 112a of said slot. Thus there is formed a discharge passage 11215 between said hopper and said slot 112 which provides a free and unobstructed passage to and through said slot 112 whereby there will be no shelf portion or plateau to permit any buildup or accumulation of material feeding therethrough. The bottom curvature 94a of the door 94 conforms to that of said slot 112.

Operation One of the improvement elements of construction embodied in the applicants device is the particular tear drop design of the screen 53. The screen is easily handled. By removing the angle plate 56 the screen is readily nested for storage purposes. In use this screen permits a full circle grinding operation without any buildup of material on the inner surface of the screen. As the material is brought upwardly by the action of the hammers it is thrown into the free space area at the apex of the screen out of contact with the blades free to drop downwardly directly into the blades for continuous grinding action until reduced to a size to permit it to pass through the mesh of the screen and to drop into the discharge outlet.

The screen is readily mounted in operating position supported on the arm bracket 50 and the flange 48. Overlying the open side of said screen is a cover member 63 having the substantial aperture 66 therein in axial alignment with the hammer assembly 45. Thus within the screen is formed the grinding chamber 60. About the screen and within the housing portion 20 is the chamber 31 enclosed by the door or cover member 68 with said cover member carrying hold down screws 74 to secure the screen cover 63 in position.

Chamber 31 forms the air circulation chamber about the grinding chamber 66. A requirement for a good grinding operation is a good circulation of air throughout the grinding chamber. Absent a good circulation of air there is a tendency for the material therein to clog the mesh of the screen and to have a tendency to build up therein. Thus the applicant combines two improved features to bring about a more efficient grinding operation. These features are the tear drop screen design and the air circulation chamber in cooperation therewith. The direction of air flow is indicated by arrows in FIG. 4. The action of the hammers creates an area of low pressure at the inner side of the apertured portion of the cover plate 63 which results in a steady stream of air being drawn inwardly through the aperture 66, said hammers moving said air through the screen as a part of the grinding operation. Thus there is a steady recirculation of air of such an efficient nature that it has been found that there is very little if any need for the use of a dust collector in connection with the device.

A third element of improved construction in applicants device is the design of the inlet slot 112 through which material is fed into the grinding chamber. The particular design of the slot and the passage directly in connection therewith avoids any buildup of material which might otherwise clog the inlet. One of the problems faced with a slot of usual rectangular configuration is that the action of the hammers and the air pressures created thereby tend to block the opening of the slot and prevent the free movement of material into the grinding chamber. It is noted here that the passage 11% in connection with said slot has a downward curvature terminating by merging into the wall 18 and thereby into the plane of the slot. The curvature of the slot 112 follows generally the path described by the hammers in action. Thus during a grinding operation the hammers in moving air across the face of said slot 112 tend to create a low pressure area thus encouraging a free flow of material, and the action of said hammer tends to withdraw material from the passage feeding through the slot 112. The arrangement set forth provides a very eflicient flow of material into the grinding chamber.

Thus the applicant in a simply constructed and efficiently designed hammer mill grinding device provides a substantial improvement in the grinding operation thereof. This device has been very successful in commercial use and represents a substantial improvement in the grinding art.

It will of course be understood that various changes may be made in the form, details, arrangement and proportions of the parts, Without departing from the scope of applicants invention which, generally stated, consists in a device capable of carrying out of the objects above set forth, in the parts and combinations of parts disclosed and defined in the appended claims.

What is claimed is:

1. In a grinding apparatus having in combination,

a housing,

said housing having a grinding chamber formed therein,

a hopper in connection with said housing,

said grinding chamber and said housing having a common Wall, said grinding chamber comprising a screen, said screen being formed of sheet screen material substantially rectangular in blank and formed into an endless collar-like member having a tear drop configuration in plan with the apex thereof being uppermost,

means mounting said screen to have one open side thereof bearing against said common wall,

a cover overlying the other open side of said screen,

said cover having an aperture therein,

a plurality of hammers within said grinding chamber,

means rotatively supporting said hammers about an axis in alignment with said aperture in said screen cover,

an inlet into said grinding chamber formed as an arcuate slot in said common wall, a passage connecting said hopper and said inlet, said passage having a depth tapering in width longitudinally of said inlet and merging therewith to become flush with the face portion of said inlet at one end portion thereof, said inlet defining an are having a radius substantially equivalent to the radius of the path described by said hammers and being parallel to said path and closely adjacent the hammers nearest thereto,

said inlet discharging in the direction of rotation of said hammers,

an outlet in said housing receiving material from said grinding chamber and discharging the same, and said housing having an air circulation chamber about said grinding chamber.

2. In a grinding apparatus having in combination,

a housing,

an endless belt-like screen of some width having a tear drop configuration in plan with the apex thereof being uppermost,

means in connection with an upstanding wall of said housing supporting said screen thereon, said wall overlying one open side of said screen and said screen forming grinding chamber therein,

a cover overlying the other open side of said screen,

said cover having an aperture therein,

grinding means rotatively mounted within said grinding chamber,

said housing having an air circulation chamber therein about said screen,

an inlet into said grinding chamber comprising an arcuate slot within said wall, said slot having a radius on the order of the radius of the path described by said grinding means,

a hopper in connection with said inlet, and

a feeding passage connecting said hopper with said inlet, said passage having a bottom wall having longitudinally the curvature of said arcuate slot being disposed in a plane at an angle to the plane thereof and having a side Wall portion which together with said bottom wall tapers in the direction of one end portion of said inlet to merge and become flush with the face portion of said inlet whereby no shelf portion is present in said end portion of said passage for the buildup of material therein.

3. In a grinding apparatus having in combination,

a housing,

an endless screen substantially rectangular in blank,

means mounting said screen to have one open side thereof overlie a vertical wall of said housing,

a cover overlying the other open side of said screen,

said cover having an aperture therein,

said screen forming a grinding chamber therein,

rotatable grinding means having a horizontal axis mounted in said grinding chamber,

said housing having an air circulation chamber therein about said screen,

said wall having an elongated vertically disposed arcuate slot opening into said grinding chamber,

means carried by said wall for adjusting the opening of said slot,

a hopper carried by said Wall in communication with said slot, and

said slot having a curvature having a radius substantially on the order of the radius of the path described by said grinding means.

4. The structure set forth in claim 3,

said third mentioned means including an arm extending outwardly of said wall, and

a flange projecting from said wall having a configuration to receive said screen thereon, said arm being disposed at a point uppermost of said flange.

5. The structure set forth in claim 3,

a passage connecting said hopper and said slot,

said passage having a bottom Wall integral with the lower Wall portion of said slot and having longitudinal curvature identical therewith, said bottom wall tapering longitudinally of said slot to merge therewith at one end portion thereof into the plane thereof, and

a side wall portion integral with said bottom wall of said passage and merging with said end wall portion of said slot into the plane thereof.

6. In a grinding apparatus having in combination,

a housing,

an endless screen rectangular in blank formed to be of a tear drop configuration in plan,

means mounting said screen to have one open side thereof overlie a wall of said housing,

a cover overlying the other open side of said screen,

said cover having an aperture therein,

said screen forming a grinding chamber therein,

rotatable grinding means mounted in said grinding chamber,

said housing having an air circulation chamber about said screen,

a cover mounted on said housing spaced from said first cover,

means removably securing said cover to said housing,

'7 8 adjustable holding means carried bysaid second cover References Cited by the Examiner sjcurlii'lig1 said first nlientioned cover, h b UNITED STATES PATENTS sai Wa aving an in ct into said grinding c am er, a hopper in connection with said housing, 2013378 9/1935 Dressel 241*86 X a passage connecting said hopper and said inlet, 5 1068383 1/1937 Lmdgren 241*86 said passage having a bottom Wall integral with the 21611600 11/1952 Cole 241*88 lower wall of said inlet, said bottom Wall merging 21640650 6/1953 Jacobson 241 89 into the plane of said inlet, said passage having a side 27341687 2/1956 Draws 241 '186 wall portion coextensive with said bottom wall being A inclined in the direction thereof and merging into the ROBERT RIORDON Prlma'y Exammer' plane of said inlet. H. F. PEPPER, 111., Assistant Examiner. 

1. IN A GRINDING APPARATUS HAVING IN COMBINATION, A HOUSING, SAID HOUSING HAVING A GRINDING CHAMBER FORMED THEREIN, A HOPPER IN CONNECTION WITH SAID HOUSING, SAID GRINDING CHAMBER AND SAID HOUSING HAVING A COMMON WALL, SAID GRINDING CHAMBER COMPRISING A SCREEN, SAID SCREEN BEING FORMED OF SHEET SCREEN MATERIAL SUBSTANTIALLY RECTANGULAR IN BLANK AN FORMED INTO AN ENDLESS COLLAR-LIKE MEMBER HAVING A TEAR DROP CONFIGURATION IN PLAN WITH THE APEX THEREOF BEING UPPERMOST, MEANS MOUNTING SAID SCREEN TO HAVE ONE OPEN SIDE THEREOF BEARING AGAINST SAID COMMON WALL, A COVER OVERLYING THE OTHER OPEN SIDE OF SAID SCREEN, SAID COVER HAVING AN APERTURE THEREIN, A PLURALITY OF HAMMERS WITHIN SAID GRINDING CHAMBER, MEANS ROTATABLY SUPPORTING SAID HAMMERS ABOUT AN AXIS IN ALIGNMENT WITH SAID APERTURE IN SAID SCREEN COVER, AN INLET INTO SAID GRINDING CHAMBER FORMED AS AN ARCUATE SLOT IN SAID COMMON WALL, A PASSAGE CONNECTING SAID HOPPER AND SAID INLET, SAID PASSAGE HAVING A DEPTH TAPERING IN WIDTH LONGITUDINALLY OF SAID INLET AND MERGING THEREWITH TO BECOME FLUSH WITH THE FACE PORTION OF SAID INLET AT ONE END PORTION THEREOF, SAID INLET DEFINING AN ARC HAVING A RADIUS SUBSTANTIALLY EQUIVALENT TO THE RADIUS OF THE PATH DESCRIBED BY SAID HAMMERS AND BEING PARALLEL TO SAID PATH AND CLOSELY ADJACENT THE HAMMERS NEAREST THERETO, SAID INLET DISCHARGING IN THE DIRECTION OF ROTATION OF SAID HAMMERS, AN OUTLET IN SAID HOUSING RECEIVING MATERIAL FROM SAID GRINDING CHAMBER AND DISCHARGING THE SAME, AND SAID HOUSING HAVING AN AIR CIRCULATION CHAMBER ABOUT SAID GRINDING CHAMBER. 